IB Biology Quiz: Concluding And Evaluating

What this quiz covers

This quiz focuses on Concluding And Evaluating, giving you a quick way to practice the rules, question types, and explanations that matter most for IB Biology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. The null hypothesis is accepted, indicating the distribution of the snail is random and not associated with the alga.
2. The null hypothesis is rejected, suggesting there is a statistically significant association between the snail and the alga. (correct answer)
3. The experiment has a 4% chance of being incorrect, so the results are inconclusive and should be repeated with a larger sample size.
4. The alternative hypothesis is accepted, proving that the snail's presence is directly caused by the availability of the alga.

Question 2

1. The percentage increase of 15% is not high enough to be considered statistically significant without a p-value.
2. The experiment should have included a third field using a traditional, well-established fertilizer for comparison.
3. Potential confounding variables, such as differences in soil composition or water drainage between the fields, were not controlled. (correct answer)
4. The conclusion is invalid because the experiment was not repeated over multiple growing seasons to ensure reliability of the results.

Question 3

1. An unchanged Km indicates the inhibitor does not bind to the active site, and a reduced Vmax shows the enzyme's catalytic efficiency is lowered. (correct answer)
2. A reduced Vmax suggests the inhibitor binds irreversibly to the active site, while an unchanged Km indicates saturation is still possible at high substrate concentrations.
3. The unchanged Km shows that the substrate's binding affinity is unaffected, while the reduced Vmax is because high substrate levels can outcompete the inhibitor.
4. A reduced Vmax means fewer enzyme molecules are available, and an unchanged Km shows the inhibitor has the same shape as the substrate, fitting the active site.

Question 4

1. The claim is fully supported, as the evidence of stasis followed by rapid change is the defining feature of punctuated equilibrium and contradicts gradualism.
2. The claim is weak because gradual changes could have occurred in soft tissues that were not fossilized, so the true evolutionary pattern is unknown.
3. The claim is an overstatement; while the evidence strongly supports punctuated equilibrium in this specific lineage, it does not invalidate gradualism as a possible mode of evolution in other lineages. (correct answer)
4. The claim is false because 'rapid' geological change can still represent thousands of years of gradual evolution that only appears abrupt in the fossil record.

Question 5

1. DNA is the genetic material because nucleotides contain nitrogen, which was incorporated into the bacterial pellet.
2. Protein is the genetic material because amino acids contain nitrogen, which was incorporated into the bacterial pellet.
3. The experiment is inconclusive because both DNA (in bases) and protein (in amino acids) contain nitrogen. (correct answer)
4. The experiment proves that the phage coat, not the genetic material, is injected into the bacterium during infection.

Question 6

1. Fish-eating birds are more susceptible to the toxic effects of DDT than organisms at lower trophic levels.
2. The concentration of DDT increases at successively higher trophic levels, demonstrating the process of biomagnification. (correct answer)
3. DDT is a biodegradable substance that is gradually broken down as it moves up the food chain.
4. Organisms at each trophic level bioaccumulate DDT from their environment at approximately the same rate.

Question 7

1. The toxin blocks voltage-gated sodium channels on the axon of the motor neuron.
2. The toxin blocks the influx of calcium ions into the presynaptic terminal.
3. The toxin inhibits the enzyme acetylcholinesterase in the synaptic cleft.
4. The toxin binds to and blocks the neurotransmitter receptors on the postsynaptic membrane. (correct answer)

Question 8

1. The disorder is autosomal recessive because it appears in every generation.
2. The disorder is autosomal dominant, and X-linked dominant inheritance can be conclusively ruled out. (correct answer)
3. The disorder is X-linked dominant because affected fathers pass the trait to all their daughters.
4. The disorder is X-linked recessive, but the possibility of it being autosomal recessive cannot be eliminated.

Question 9

1. The peas may have been conducting both aerobic and anaerobic respiration, thus consuming less oxygen than predicted. (correct answer)
2. The temperature of the water bath may have been lower than 25°C, reducing the metabolic rate of the peas.
3. The amount of potassium hydroxide was insufficient, allowing CO₂ pressure to counteract the drop in O₂ pressure.
4. The respirometer was not properly sealed, allowing atmospheric oxygen to leak into the apparatus during the experiment.

Question 10

1. Type 2 diabetes is primarily a genetic disease, with environmental factors playing only a minor role in its development.
2. Environmental factors are the main cause of type 2 diabetes, as the concordance rate is not 100%.
3. The expression of genes related to diabetes is controlled by epigenetic markers that differ between the twins.
4. The development of type 2 diabetes is influenced by both a significant genetic predisposition and significant environmental factors. (correct answer)

Question 11

1. The finches with larger beaks evolved through natural selection in a single generation in response to the drought.
2. The drought induced mutations in the finches, causing them to develop larger beaks to eat the available seeds.
3. The change in seed availability acted as a selection pressure, favouring the survival of pre-existing finches with larger beaks. (correct answer)
4. All finches with small beaks died during the drought, leaving only large-beaked finches to reproduce.

Question 12

1. Larger islands may have higher rates of mutation, leading to faster speciation and greater biodiversity.
2. Larger islands present a larger target for colonization by new species from the mainland, leading to higher immigration rates. (correct answer)
3. Smaller islands have harsher environmental conditions, leading to greater competition among the species that live there.
4. Smaller islands have higher rates of extinction because their coastlines are more exposed to natural disasters.

Question 13

1. The principles of osmosis are reversed at very high solute concentrations, causing water to move against its concentration gradient.
2. The anomalous data point is likely due to a systematic error in the experimental procedure, such as incorrect solution preparation for all samples.
3. This result suggests that potato cells actively transport sucrose inwards when the external concentration exceeds a certain threshold.
4. The potato cylinder used for the 0.8 M solution may have had a significantly different initial water potential or was not properly blotted. (correct answer)

Question 14

1. High consumption of processed meats is a major cause of colorectal cancer in the studied population.
2. Individuals who consume less processed meat are guaranteed to have a lower risk of developing colorectal cancer.
3. There is a significant statistical association, suggesting that lifestyle factors related to meat consumption may influence cancer risk. (correct answer)
4. The chemicals used to preserve processed meats have been proven to be carcinogenic by this correlational study.

Question 15

1. Can the therapy be delivered efficiently and safely to the target lung cells in a living human organism? (correct answer)
2. Is the CRISPR-Cas9 system capable of correcting other genetic diseases besides cystic fibrosis?
3. What is the precise molecular mechanism by which the Cas9 enzyme cuts the target DNA sequence?
4. Can the corrected lung cells be grown in sufficient quantities in the lab to be commercially viable?

Question 16

1. The sample size of 10 individuals is too small to draw any meaningful conclusions about human physiology.
2. The two-hour time frame is insufficient to observe the long-term homeostatic effects of the insulin injection.
3. The absence of a control group receiving a saline injection makes it impossible to attribute the change solely to insulin. (correct answer)
4. Measuring blood glucose every 15 minutes is not frequent enough to accurately capture the dynamics of glucose change.

Question 17

1. The experiment only demonstrates a correlation; it does not prove that the plant naturally produces ABA in response to water stress. (correct answer)
2. The ABA was applied externally, which may not accurately mimic the internal physiological concentration and transport within the plant.
3. The use of a well-watered plant is inappropriate, as the effects of ABA should only be tested on plants already experiencing drought.
4. The conclusion is invalid because stomatal closure could have been caused by other environmental factors in the laboratory.

Question 18

1. The rRNA evidence should be prioritized as it reflects evolutionary lineage, supporting classification as a fungus. (correct answer)
2. The presence of a cell wall and lack of chloroplasts means it must be a plant that has lost its photosynthetic ability.
3. The organism should be placed in a new kingdom because it shares features of both fungi (chitin) and protists (unicellular).
4. The mode of reproduction (budding) is the most important feature, confirming its classification within the yeasts.

Question 19

1. 90% of individuals who receive the vaccine will be completely immune to the disease.
2. Receiving the vaccine reduces an individual's risk of contracting the disease by 90% compared to being unvaccinated. (correct answer)
3. There is a 10% chance that a vaccinated person will contract the disease during the trial period.
4. The vaccine is effective in only 90% of the population, while 10% of people will not respond to it at all.

Question 20

1. Chlorophyll a and b are less efficient at converting light energy into chemical energy in the green-yellow region.
2. Accessory pigments, such as carotenoids, must be absorbing light in the green-yellow region and transferring the energy to the reaction centers. (correct answer)
3. The experimental measurement of oxygen production is an inaccurate method for determining the rate of photosynthesis in green-yellow light.
4. Photosynthesis is primarily driven by light intensity, not wavelength, and the green-yellow light used must have been of a higher intensity.